Dental floss and method of making same

ABSTRACT

A polyester elastomer is extruded into a hot and tacky tape having certain tensile properties when cooled, including a high degree of stretchability; and by subsequent stretching of the cooled product, its break strength is substantially increased while it develops desirable elastomeric properties. The tape is cut into strips of dental floss of 1- 1/2 to 10 mils thickness either before or after the stretching, and abrasive particles and a flavoring agent may be incorporated into the tape material or applied to the tape surface.

United States Patent Jaffe 1 Apr. 2, 1974 1 DENTAL FLOSS AND METHOD OF 3,511,249 5 1970 Baitz 132/89 MAKING SAME 2,381,142 8/1945 Stonehill 132/89 [75] Inventor: Paul E. Jaffe, Scarsdale, NY. Primary Examiner RuSSe" R. Kinsey [73] Assignee: Pauldan Industries, Inc., New York, Assis ant Examiner-Gregory E. MCNeill NY. 22 Filed: Nov. 27, 1972 [57] ABSTRACT A polyester elastomer is extruded into a hot and tacky [21] App! 309878 tape having certain tensile properties when cooled, including a high degree of stretchability; and by subse- [52] 11.8. C1. 132/89 qu n stretching of the cooled p i break [51] Int. Cl. A6lc 15/00 ng h is tan i lly increa ed while it develops de- [58] Field of Search 132/89, 90, 91; 424/67; sirable elastomeric properties. The tape is cut into 167/93 strips of dental floss of 1-% to 10 mils thickness either before or after the stretching, and abrasive particles [56] References Cited and a flavoring agent may be incorporated into the UNITED STATES PATENTS tape material or applied to the tape surface.

1 1954 Ashton 167/93 13 Claims, No Drawings DENTAL FLOSS AND METHOD OF MAKING SAME This invention relates to dental floss and more particularly to an improved dental floss which, as compared to conventional products of this type, is softer and more gentle in its tooth cleansing action and yet is more effective for cleaning interproximal tooth surface areas.

Toothbrushes are not suited for penetrating the restricted regions between closely adjacent teeth. Accordingly, it is common practice to use dental floss to supplement toothbrushing, in order to remove food particles held between the teeth. However, conventional dental floss has several objectionable features inhering from its construction, which consists of multistrand yarns coated with a wax-like substance. For example, it is quite resistant to deformation of its crosssectional area, so that it is poorly adapted to accommodate variations in inter-tooth contact pressures; and it provides a harsh cleansing action at best.

The principal object of the present invention is to provide a dental floss which eliminates these objectionable features and which is well suited to incorporate a flavoring agent and/or mild abrasive material.

A dental floss made according to the invention comprises a strip of elastomer, preferably polyester elastomer, with a thickness of 1-% to mils and having the following tensile properties:

a. Modulus of elasticity in tension, in the longitudinal direction, of 4,000 to 10,000 psi, preferably 5,000 to 6,000 psi.

b. Minimum break strength of 7,000 psi, preferably 1 1,500 to 14,000 psi.

c. Ultimate elongation of 200 to 1,000 percent, preferably 275 to 350 percent.

1 have found that in the use of a dental floss with these characteristics, it does not stretch excessively or break and yet is readily deformable in cross-section so that it can quite easily enter inter-tooth regions which are difficult to reach with conventional dental floss. Moreover, it provides a gentle cleansing action which is highly effective regardless of variations in the intertooth contact pressures or clearances, because upon reduction of the relatively high tension to which it is subjected when applying it between teeth, it tends to expand more or less against the adjacent teeth surfaces, depending upon the amount of such contact pressure or clearance.

The elastomer may be of various kinds. Polyester elastomer is preferred, but other examples are silicon polycarbonates, styrene butadienes, styrene ethylene propylenes; polypropylenes and thermoplastic polyurethanes. l have found that an elastomer particularly well suited for the new dental floss is a polyester elastomer sold by Du Font and known as Hytrel, which is a polycondensation product made by condensing at least one aromatic dicarboxylic acid or its ester having a molecular weight below 300 with a polyalkylene ether glycol having a molecular weight of 400 to 6,000 and at least one diol having a molecular weight below 250.

Preferably the new dental floss is made from the Bytrel elastomer which is sold by Du Pont as Hytrel 4055. This material may be extruded into film which is unstretched and which has the following tensile properties when cooled to room temperature:

a. Modulus of elasticity in tension in the order of 5,300 to 5,700 psi. b. Break strength in the order of 7,200 to 7,500 psi.

c. Ultimate elongation in the order of 750 to 850 percent.

d. No significant yield.

To provide this fllm with the preferred properties of the new dental floss, it is stretched longitudinally (i.e., in the direction in which it was extruded) approximately 350 percent, thereby modifying these properties to the following values:

a. Modulus of elasticity in tension, in the longitudinal direction, in the order of 5,300 to 5,700 psi.

b. Break strength in the order of 11,500 to 14,000

0. Ultimate elongation in the order of 300 to 350 percent.

d. No significant yield.

In the preferred embodiment of the invention, the strip of elastomer dental floss is provided with a pulverized abrasive and a flavoring agent. The latter may be incorporated in the elastomer before or during its extrusion into film or by coating the extruded film. These abrasive and flavoring additives may be a conventional tooth powder and are preferably sprayed upon a film or tape of the elastomer while it is still hot and tacky from the extruder which forms it, although the additives may be applied to the film or tape while it is reheated after being extruded and cooled. After cooling of the extruded film or tape (hereinafter referred to collectively as tape), it is cut into strips of dental floss having the aforementioned thickness of 1- /2 to 10 mils. In cases where the tape must be stretched to provide it with the tensile properties according to the invention (as in the case of Hytrel 4055 film), the stretching may be effected between the cooling and cutting steps or after the cutting step.

An example of the pulverized abrasive additive is calcium carbonate having a particle size of 0.1 to 2.0 microns, which may be added in an amount constituting about three percent by weight of the dental floss strip. Examples of the flavoring agent are peppermint oil, Spearmint oil and Wintergreen oil, and it may be added in any desired amount.

The elastomer forming the new dental floss preferably has a tack temperature above 200F (the tack temperature of the Hytrel 4055 tape being about 230-235F). This enables it to become sufficiently tacky from the heat of extrusion of the tape so that the additives will become firmly embedded in the tape surfaces after cooling and will remain firmly embedded in the uncut surfaces of the dental floss strips under normal conditions.

The abrasive additive serves as an aid in cleansing between teeth. As an alternative, however, the surfaces of the tape may be roughened prior to cutting of the strips of dental floss, as by sand-blasting or stippling or by rolling impressions on the surfaces.

The new dental floss may have any desired crosssectional configuration, such as round, oval, square or rectangular; and it will be understood that the thickness dimension of l-% to 10 mils applies to the diameter of a round configuration, to the spacing between opposing sides of a square configuration, and to the minimum spacing between opposing sides of an oval or rectangular configuration. Preferably, the cross-section is a rectangular one having a maximum dimension (width) of H16 to Ms inch.

cent of original length at which break occurs in the tensile test.

As previously mentioned, the Hytrel 4055 elastomer is particularly well suited for the manufacture of the new dental floss. This elastomer in the unstretched form behaves like a plastic material in that it has a distinct yield point in tension. The elongation at the yield point is considerably below 350 percent. In stretching to 350 percent, the material is therefore stressed beyond its yield point and permanent elongation takes place. Because the tensile strength beyond the yield point is so much greater than the yield strength, the permanent elongation is substantially unifonn throughout the length of the specimen. This is an unusual property for a material to possess at room temperature, which apparently contributes significantly to the success of the material for use as dental floss according to the invention. In the region on the stress-strain curve between the yield point and failure, that is, in the stretched form, the material can be said to behave like an elastomer. As is characteristic of elastomers, there is no apparent yield point in this region.

I claim:

1. A dental floss comprising a strip of elastomer with a thickness of l-% to mils, said strip having the following tensile properties:

a. Modulus of elasticity in tension, in the longitudinal direction, of 4,000 to 10,000 psi.

b. Minimum break strength of 7,000 psi.

c. Ultimate elongation of 200 to 1,000 percent.

2. A dental floss according to claim 1, in which said modulus is 5,000 to 6,000 psi, the break strength is 11,500 to 14,000 psi, and the ultimate elongation is 275 to 350 percent.

3. A dental floss according to claim 2, in which said elastomer is a polyester which is a polycondensation product made by condensing at least one aromatic dicarboxylic acid or its ester having a molecular weight below 300 with a polyalkylene ether glycol having a molecular weight of 400 to 6,000 and at least one diol having a molecular weight below 250.

4. A dental floss according to claim 1, in which said strip has a tack temperature above 200F.

5. A dental floss according to claim 1, comprising also a flavoring agent carried by said strip.

6. A dental floss according to claim 1, comprising also a pulverized abrasive material carried by said strip.

7. A dental floss according to claim 6, in which said abrasive material has a particle size of 0.1 to 2.0 microns and constitutes about 3 percent by weight of the strip.

8. A method of making dental floss, which comprises extruding a polyester elastomer into a hot and tacky tape which, when cooled, is untacky and has the following tensile properties:

a. Modulus of elasticity in tension in the order of 5,300 to 5,700 psi. b. Break strength in the order of 7,200 to 7,500 psi. 0. Ultimate elongation in the order of 750 to 850 percent, cooling the extruded tape, cutting the tape into strips having a thickness of l-% to 10 mils, and stretching the material from one of said cooling and cutting steps to increase said break strength to about 11,500 to 14,000 psi, thereby reducing said ultimate elongation to about 300 to 350 percent.

9. A method according to claim 8, in which said elastomer is a polycondensation product made by condensing at least one aromatic dicarboxylic acid or its ester having a molecular weight below 300 with a polyalkylene ether glycol having a molecular weight of 400 to 6,000 and at least one diol having a molecular weight of 400 to 6,000 and at least one diol having a molecular weight below 250.

10. A method according to claim 8, comprising also the step of applying a pulverized abrasive material to said polyester elastomer.

11. A method according to claim 8, comprising also the step of applying a flavoring agent to said polyester elastomer.

12. A method according to claim 8, in which said stretching is effected after said cooling but prior to said cutting.

13. The method of claim 8, in which said stretching is effected after said cutting. 

2. A dental floss according to claim 1, in which said modulus is 5,000 to 6,000 psi, the break strength is 11,500 to 14,000 psi, and the ultimate elongation is 275 to 350 percent.
 3. A dental floss according to claim 2, in which said elastomer is a polyester which is a polycondensation product made by condensing at least one aromatic dicarboxylic acid or its ester having a molecular weight below 300 with a polyalkylene ether glycol having a molecular weight of 400 to 6,000 and at least one diol having a molecular weight below
 250. 4. A dental floss according to claim 1, in which said strip has a tack temperature above 200*F.
 5. A dental floss according to claim 1, comprising also a flavoring agent carried by said strip.
 6. A dental floss according to claim 1, comprising also a pulverized abrasive material carried by said strip.
 7. A dental floss according to claim 6, in which said abrasive material has a particle size of 0.1 to 2.0 microns and constitutes about 3 percent by weight of the strip.
 8. A method of making dental floss, which comprises extruding a polyester elastomer into a hot and tacky tape which, when cooled, is untacky and has the following tensile properties: a. Modulus of elasticity in tension in the order of 5,300 to 5, 700 psi. b. Break strength in the order of 7,200 to 7,500 psi. c. Ultimate elongation in the order of 750 to 850 percent, cooling the extruded tape, cutting the tape into strips having a thickness of 1- 1/2 to 10 mils, and stretching the material from one of said cooling and cutting steps to increase said break strength to about 11,500 to 14,000 psi, thereby reducing said ultimate elongation to about 300 to 350 percent.
 9. A method according to claim 8, in which said elastomer is a polycondensation product made by condensing at least one aromatic dicarboxylic acid or its ester having a molecular weight below 300 with a polyalkylene ether glycol having a molecular weight of 400 to 6,000 and at least one diol having a molecular weight of 400 to 6,000 and at least one diol having a molecular weight below
 250. 10. A method according to claim 8, comprising also the step of applying a pulverized abrasive material to said polyester elastomer.
 11. A method according to Claim 8, comprising also the step of applying a flavoring agent to said polyester elastomer.
 12. A method according to claim 8, in which said stretching is effected after said cooling but prior to said cutting.
 13. The method of claim 8, in which said stretching is effected after said cutting. 